Electrical vibrating motor



Aom. 21, 1930 y .,F. cUTTlNVGEr/u. 1,779,114

A 'ELECTRICAL VIBRATING- MOTOR 'Filed April' 9, 1929 INVENTORSl .FULTONCUTTNG BY IOURY G. MALOFF Patented Oct. 21, 1930 UNITED s'-'1a .'11: sIPATENT 'o1-"F1os FULTON CUTTING, 01 NEWYOBK; AND'IOIURY G. MALOFF, OFWHITE PLAINS, NEW'y YORK; SAID MALOFF -ASSIGNOB T UNITED BEPRODUCEBSCORPORATION, 0F

ROCHESTER, NEW'YOBK, CORPORATION OF NEW JERSEY..

VIBRATING MOTOR This invention relates broadly to an electromechanicalvibrating' motor, and more particularly to a sound reproducing systemutilizing such a motor.

6 It is an object of this invention to provide such a motor in which thelosses heretofore usual are eliminated or very substantiall reduced, andin which, as a result, the e iciency is greatly increased.

It isa further object of our invention to provide ha device of the classdescribed, which shall be extremelyfsimple vand economical inconstruction, rugged and reliable in operation, and capable ofmanufacture and assembly without requiring extremely precise and`careful workmanship.

Still other objectsand advantages o f our invention will be -apparentfrom the specifica- The features .of novelty which we believe to becharacteristic of our invention' are set forth with particularity in theappended claims. Our invention itself, however, both as to itsfundamental principles and as to its particular applications will bestbe understood by reference to the y'specification and' accompanyingdrawing, in which Figure 1 is a diagrammatic view of a .sys tern inaccordance with `our`invention and showing ak sound reproducer partlybroken away. A l F1gure 2 is an elevation view of a drlvlng motor inaccordance with our invention showing the sound radiating,y diaphragmremoved.

Figure 3 is an exploded perspective view .of the vibrating systemutilized in accord*- ance with our invention; and, l Y Figure 4 is aperspective view of the secondary of the transformer utilized forsupplying currents to the sound reproducer.

. I In Aaccordance with our invention, we utilize a vibratin motorconsisting of a conductor mounte in a magnetic field andl supplied withcurrents which it jis desired to* convert into motion. Preferably,although not necessarily', the vibrating conductor is in the form ofaring or coil mounted for axial motion in an air gap-of correspondingshape. In devices of the class described as heretofore utilized, thevibrating' coil has been Appleman mea Apri; s, 192s. sum1 No. 268,776.

formed by being wound up of a number of turns of relatively tine wire.The fine wire utilized requires a coil -form `or support to hold thewinding in shape, and it has kresulted in the past, that a considerableportion of the space in thel air gaphas been taken up by thewindingsupport, which contributes nothing to the operation of thediaphragrn. This has, in turn, resulted in the proportional part of theair gap occupied by the active conductors driving the diaphragm beingrelatively much smaller than desired, with theresult that a considerablygreater "field strength has been required than would have been necessaryif such a support were not used. This, in turn, has required the use ofa larger and more' expensive magnetic structure forfa ypredetermmedsound output or an increase in the' power supplied to the vibrating coilwith a consequent 1ncrease in -thecost of apparatus for supplyingthecurrents.,

In accordance with our invention, we

utilize a conductor which is of suiiicient size and strengthtomaintainits form andshape Without additional support, therebypermittingv the use of a considerably greater amount of copper in theconductor with normal clearancesin the air gap than has heretofore'beenpossible. We also provide the conductor with extensions attached.thereto and preferably'forined integral therewith, which eXtensions formthe leads supplying current to the coil and which are preferably but'not necessarily made suliciently stiff and strong to act as the supportfor the vibrating coil. By

forming and shaping the leads in a manner rably from a single v 3 havin.a-central o eningth g piece 2 and. defining anali-'- 1, 1 designates acasing4 of magnetic material, such "for-*example as [iron orjoth'er;suitable magnetic. material, having 'an' inner projec-j tion o'r-'p'olepiece 2, andp'rovided' lwith' a cover" rein, surrounding the inner pole'nu ar. air gap 4, in 'edforvibration.

` and 7, `which formthe .leadsforsupplying currents to the coil 5.Extensions 6 and7 are secured to a support,`such for example as cross.

members 8 and 9 mounted upon the top plate 3 ofthe magnet and heldfirmly in position by v screws -and 11, which clamp the top clamp 4bakelite, held in position on 8 upon the bottom member 9. -The clamps 8and 9, if of metal, will be insulated from one or both of the extensionsGiand 7 to prevent short circuiting. of the coil 5; in addition, a brace12 secured to the leads 6 and Z may be used-to increase the rigidity, ofthe leads and to-prevent undesired motion Without interfermg with thenormal lvibration thereof. The brace 12 may be in the form 'of'a stripof the leads 6 and 7 b screwsl .13 4and 14;,

or the purpose of radiating sound, 'a carrier ring 18 of suitablematerial, such as bakelite, may be mounted upon .the conductor 5.

The ring 18 `will'preferably be of substan.

. tially the same size and thickness -as the conductor 5, and isprovided at its lower edge with notches`19 and 20, and anadditionalnotch, not shown, which receive the projections 16 and 417 on theconductor 5, and also -receive the inner ends of the leads 6 and 7.

The ring 18 is secured in position, for example, by cementing, and asuitable sound radiating diaphragm, such. as cone 21 is secured to thering 18, as for example by means of flange 22 inserted within the ring18 and cemented. v

The coill is vfed from the transformer 23 having a primary Winding 24, asecondary winding 25, and a core of magnetic material 26. In theoperation of the sound reproducer in its preferred form, the `currentsto be reproduced are supplied to the input circuit 40 of a thermionicvacuum' tube amplifier 41 by means of the primary winding 39 leading tothe source of currents. The vacuum tube amplifier comprises an anode 42,a control electrode 34 and a cathode 35. The outputcircuit is energizedby a suitable source of potential 36, and for the purpose of preventingthe flow of direct current in the primary of the transformer, a choke 37and a condenser 38 connected in the usual manner may -be utilized. Asuitable C battery 43 will usually be provided in the input circuit ofthe amplitier 32. In case the direct currentjlowing in the outputcircuit is permittedto traverse the primary winding 24, agapwillpreferably `be 'formedin the magnetic core 26 to preventsaturation thereof. l' f The secondary winding 25. ofthe transformer isin the form ofa heavy coil with a' .small number of turns, one A0 1" twobeing and by soldering if desired, care being taken to establish agood'electrical contact over a wide surface.

While the conductor 5 and the' secondary 25 are shown herein as singleturn coils, and

whilev We'prefer to. construct them in this manner this is not essentialas both may be made tohave several turns, it being borne in s mind,however, that the maximumpossible amount of copper should be used in theair gap A4, and the resistance of the secondary 25, leads 6 and 7 andcoil 5 should be kept as low' as possible.4 On the other hand, the.number of turns in the primary winding 24. will be very large andtheWinding will pref-- erably be wound of line wire; the resistance of lthesecondary 25, leads 6 and'7 should bemade much smaller than that of coil5. The

magnetic field across the air gap 4 maybe established by the use of afield winding 45 or by the use of a permanent magnetsystem,

as will be understood.

The sound radiating diaphragm 21 is herein shown asa cone, from which wehave loo obtained particularly satisfactory results, Y but it will beunderstood that other forms of sound radiating diaphragms may beutilized. ,Howeven for best results, the mass of the diaphragm 21shouldbeI kept small and its areashould be made sulficiently large sothat megaphone or`horn amplificationis not necessary. In case thecoil 5is supported independently of the driving mechanism, the leads 6 and 7may be made freely flexible, as by being formed of copper braid. It ispossible'to control the frequency response of the i'vibrating system by.suitably designing the leads 6 and 7': for` example, by increasing thestiffness, which may be done by increasing the thickness ofthe leads,the natural frequency of the vibrating system may 'be increased, andcorrespondmgly, by making the 'leads thinner, it may be lowered, also,by

the provision of notches of various sizes and in various positions,several different natural frequencies may be imparted tothe vibratingsystem as desired, in order to compensate vfor lack of uniformity in thefrequency characteristic of the associated apparatus.

' While We have, shown and' described our4 invention as applied to asound reproducer,

it will be understood that the vibrating motor herein described isessentially reversible,

I and may hev operated as a-,generator, and that it is possible toutilize the apparatus according to ourinvention in microphones,phonograph pick-ups and various other apparatus,

as will be readily understood. It will also be understood that while wehave shown and described certain preferred embodiments of our invention,that modifications and changes may be made without departing from thespirit and scope of our invention, as will be readily understood bythose skilled in the art.

We claim:-

l. An electro-magnetic vibrating motor comprising a conductor disposedin a magnetic field, and terminating in leads secured to a support, saidleads having their constants so chosen as to give the vibrating system a:to opposite ends of said ternalsupport; j

natural period of vbrationat a predetermined requency.

2. An electro-magnetic vibrating motor comprising a conductor disposedin amag netic field and terminating in leads secured to a'support, saidleads havin their constants so chosen as to give the vlbrating system aplurality oii'natural periods of vibration at predetermined frequencies.

3. An"electromagnetic vibrating motor comprising a magnet having polepieces deiining an air gap, and a conductor mounted for vibrationtherein, said conductor being of suiiicient size andv stiffness tomaintain its form Without support, and having a portion extending` outof said ap and secured to` a support, the stiffness 0% said extendingportion being sufcient to maintain the position of said conductor insaid gap While permitting vibration thereof, and having its con-v stantsso chosen as to im art to the vibrating system a predetermined)frequency characteristic.

4. A sound reproducer comprising in combination a magnet having polepieces defining an air gap; a conductor mounted for vibration in said.gap, leads ,securedto said conductor and to a sup ort, and a sounding board'of relatively li t weightsecured to saidfconductor for v1 rationthereby, said leads having their constants so chosen as to impart to thevibrating systemY a predetermined frequency characteristic.

5. 'A sound reproducer comprisin ,in combination, a rigid conductor inthe orm of a loop, open at one point, a conical sounding board oflightweight having its' apex secured to said -loop and iexible leads securedloop and to an ex- Signed at New York city in' the county-of.. NewYorkand State of New York, this 6th day of April, A. D. 1928. l

FULTON CUTTING.

IOURY MALOFF,

